Development of SO_x gas sensor utilizing the improved beta-alumina solid electrolyte

本文研究了β-Al_2O_3与稀土氧化物（Nd_2O_3，CeO_2，Pr_6O_3）的反应<11>。以稀土氧化物薄膜和Na^+-β-Al_2O_3颗粒为样品，在1073 K时，<11>Pr_6O_3与β-Al_2O_3发生了反应，并证实了一些新化合物的存在。在CeO_2的情况下，除了CeO_2和β-Al_2O_3的特征模式外，没有发现其它模式，因此认为CeO_2不与β-Al_2O_3反应，而Nd_2O_3与β-Al_2O_3反应，生成C型化合物，并随后转变为A型化合物。在1023 K下，根据电池的电导率随时间的变化，研究了x气体混合物中，实验结果表明，在1小时内，Na^+-β-Al_2O_3颗粒的表面被稳定的Na_2SO_4相所覆盖，从而确定了最佳的固体电解质为CeO_2包覆的Na^+-β-Al_2O_3颗粒。用CeO_2固体电解质包覆Na^+-β-Al_2O_3制成了SO_x气体传感器，并研究了该传感器在873和1023 K的响应特性。平衡电动势随着P_（？<so2>）尤其是。利用<so2>CeO_2发现的Na^+-bate-Al_2 O_3促进了低温下对P_3变化响应的表征。为研制实用的SO_x传感器获得了许多有益的实验结果。

The reaction between beta-alumina and rare-earth oxides (Nd_2O_3,CeO_2,Pr_6O_<11>) have been investigated. By using the thin film of rare-earth oxide and Na^+- beta-alumina pellet as samples, the following experimental results could be found. At 1073ﾟK,Pr_6O_<11> reacted with beta-alumina and the existence of some new compounds were confirmed. In the case of CeO_2 the extra pattern except the characteristic ones of CeO_2 and beta-alumina were not found and it was concluded that CeO_2 was not reacted with beta-alumina Nd_2O_3 reacted with beta-alumina and C-type compound was found and follows transformed to A-type one.The reaction between beta-alumina pellet and air-SO_x gas mixture have been investigated based on the variation of electritic conductivity of cell with time at 1023 K. The electritic conductivity changed suddenly with the gas flowing into the cell and follows kept nearly constant value it was confirmed that the surface of Na^+-beta-alumina pellet was covered by stable Na_2SO_4 phase within one hour.From above experimental results, it could be concluded that the best solid electrolyte is the Na^+-beta-alumina covered with CeO_2. The SO_x gas sensor employing Na^+-beta-alumina covered with CeO_2 solid electrolyte was constructed and the responsivility of this sensor at 873 and 1023ﾟK have been investigated. The equilibrium e.m.f. wasfound to change reliably with the change in P_<so2>. In particularly. the characterization of response to a change in P_<so2> at lower temperature was promoted by means of utilizing the Na^+-bate-alumina diskcovered by CeO_2. Many useful experimental results have been obtainedfor development the practical SO_x sensor.